Difficultly hydrolysable additives for diesel fuels



Sept. 22, 1959 0. VON SCHICKH .ETAL 2,905,540

DIFFICULTLY HYDROLYSABLE ADDITIVES FOR DIESEL FUELS Filed Feb. 7, 1957 INVENTORS. OTTO VON SCHICKH GUENTHER NOTTES mgmj iv ATT"YS United States Patent iS'IFiiiCULILY HYDROLYSABLE ADDITIVES FOR DIESEL FUELS Otto Yon Schickh and Guenther Nottes, Ludwigshafen (Rhine), Germany, assignors to Badische Anilin- & Soda-Fabrik Aktiengesellschaft, Ludwigshafen am Rhine, state of Rhineland-Pfalz, Germany Application February 7, 1957, Serial No. 638,754

Claims priority, application Germany, February 14,, 1956 11 Claims. (Cl. 44-57) This invention relates to the improvement of diesel fuels.

The increase in the consumption of diesel fuels has led in many countries to a scarcity of hydrogen-rich products so that it is often necessary to use diesel oils poor in hydrogen, such as are obtained for example by cracking, which have relatively low cetane numbers, and to raise the cetane number of these oils by the addition of ignition improvers. As additives for improving cetane numbers there have hitherto been proposed a large number of chemical compounds, including nitrates (see for example Marder: Motorenkraftstoife, page 347 et seq.)

The known nitrate-containing ignition improvers, however, have the disadvantage that in general they are relatively readily saponifiable. For example when diesel oils which contain amyl nitrate as the ignition improver most usually employed, comeinto contact with water, a hydrolysis of the amyl nitrate takes place and the nitric acid thereby split off causes a corrosion of the storage container. This corrosion is practically unavoidable especially when using diesel oils in shipping traffic, because the diesel oil comes into contact with seat water by filling up the tanks.

We have now found that nitric acid esters of hydroaromatic or cycloaliphatic alcohols are especially well suited as additives to diesel fuels. They not only increase the ignition quality of the diesel fuels but are also products which are hydrolysable only with difficulty.

As nitric acid esters of hydroaromatic or cycloaliphatic alcohols there come into question especially: cyclopentanol nitrate, cyclohexanol nitrate, the different isomers of methylcyclohexanol nitrate, the different isomers of dimethylcyclohexanol nitrate, ethylcyclohexanol nitrate, diethylcyclohexanol nitrate, c-yclooctanol nitrate and decahydronaphthol nitrate.

The fact that the nitric acid esters of the foregoing saturated cycloaliphatic alcohols are difficulty saponifiable may be seen from the following table in which the saponification numbers of amyl nitrate and cyclohexanol nitrate in an excess of half-normal methanolic caustic potash solution are given. Whereas after boiling for 6 hours at the boiling point of the methanolic caustic potash solution about by volume of the amyl nitrate has been saponified, scarcely any saponification has taken place in the case of the cyclohexanol nitrate.

As a rule the diesel fuel should contain between about 0.1% and 3 or more percent by weight of the nitric acid esters of hydroaromatic or cycloaliphatic alcohols.

i atented Sept. 22, 1959 The following examples will further illustrate this invention but the invention is not restricted to these examples.

Example 1 The increase in the saponification number in a diesel oil to which 2% by volume of amyl nitrate have been added as compared with the same diesel oil to which 2% by volume of cyclohexanol nitrate have been added may be seen from the next table.

The diesel oil is boiled for 3 hours under reflux with an excess of half-normal methanolic caustic potash solution. The cyclohexanol nitrate in the diesel oil is practically unattacked, while the amyl nitrate in the diesel oil has reacted substantially after a few hours.

TABLE GIVING SAPONIFIOATION NUMBERS OF DIESEL OIL CONTAINING 2% BY VOLUME OF AN AGENT FOR IMPROVING THE CE'IANE NUMBER Saponification Material treated number after boiling for 3 hours Diesel oil without addition 0 Diesel oi1+amy1 nitrate 16. 7 Diesel oil-l-cyclohexanol nitrate 0 Example 3 Samples of gas oil which contain 1% by volume of cyclohexanol nitrate are rolled at room temperature for an hour with seat water in rolling flasks. Strips of clean sheet iron of the same size and the same weight are pre viously laid in the flasks,

Further samples which contain 1% by volume of amyl nitrate and samples which contain no additives for increasing cetane number (blank value) are treated under the same conditions.

In the flasks containing gas oil to which amyl nitrate has been added, there is surface attack clearly visible on the sheet iron even after one hour, whereas the sheet iron in the gas oil to which 1% by volume of cyclohexanol nitrate has been added, and in the blank sample, is practically unattacked.

Example 4 The good eifect of the ignition improvers according to this invention may be seen from the following table, the additions having been made in each case to a diesel fuel having a cetane value (C.Z.) of 50:

Addition O.Z Increase in C.Z.

0.2% of eyclopentanol nitrate 57. 0 7. 0 0.5% of cyclopentanol nitrate. 64. 5 14. 5 1.0% of cyciopentano1nitrate 72.0 22.0

0.2% of cyclohexanol nitrate 56. 5 6. 5 0.5% of cyclohexanol nitrate. 64. 0 14. 0 1.0% of cyclohexanol nitrate 70.0 20. 0 2.0% of cyclohexanol nitrate 81.0 31.0

0.2% of methylcyclohexanol nitrate 56.0 6.0 0.5% of methylcyclohexanol nitrate.-. 60. 0 10. 0 1.0% of methylcyclohexanol nitrate 68.0 18. 0

0.2% of dimethylcyclohexanol nitrate 56.0 6.0 0.5% of dimethylcyclohexa-nol nitrare 61.0 11.0 1.0% of dimethylcyclohexanol nitrate 67. 0 17.0

3 Example 5 Example 6 0.5% by Weight of cyclo-octanol nitrate is added to a diesel oil having a fundamental cetane number of 50. The cetane number is increased to 60 by'this addition.

What We claim is:

1. As a new composition of matter, a diesel fuel containing the nitric acid ester of a cycloalkyl alcohol in an amount suflicient to increase the cetane number of said fuel.

2. As a new composition of matter, a diesel fuel containing the nitric acid ester of cyclopentanol in an amount sufiicient to increase the cetane number of said fuel.

3. As a new composition of matter, a diesel fuel containing the nitric acid ester of cyclohexanol in an amount sulficient to increase the cetane number of said fuel.

4. As a new composition of matter, a diesel fuel containing the nitric acid ester of a methylcyclohexanol in an amount sufiicient to increase the cetane number of said fuel.

5. As a new composition of matter, a diesel fuel containing the nitric acid ester of a dimethylcyclohexanol in an amount suflicient to increase the cetane number of said fuel.

6. As a new composition of matter, a diesel fuel containing the nitric acid ester of cyclooctanol in an amount sufiicient to increase the cetane number of said fuel.

7. Asa new composition of matter, a diesel fuel containing'the nitric acid ester of decahydronaphthol in an amount sufiicient to increase the cetane number of said fuel.

8. As a new composition of matter, a diesel fuel containing the nitric acid ester of an ethylcyclohexanol in an amount suflicient to increase the cetane number of said fuel.

, 9. As a new composition of matter, a diesel fuel containing about 0.1% to 3% by weight of the nitric acid ester of a cycloalkyl alcohol.

10. As a new composition of matter, a diesel fuel containing about 0.1% to 3% by weight of the nitric acid ester of an alkylcyclohexanol.

11. As a new composition of matter, a diesel fuel containing about 0.1% to 3% by weight of the nitric acid ester of cyclohexanol.

References Cited in the file of this patent UNITED STATES PATENTS 2,031,497 Marvel Feb. 18, 1936 2,280,217 Cloud Apr. 21, 1942 2,560,904 Sugimoto July 17, 1951 2,645,079 Doumani et al July 14, 1953 

1. AS A NEW COMPOSITION OF MATTER, A DIESEL FUEL CONTAINING THE NITRIC ACID ESTER OF A CYCLOAKYL ALCOHOL IN AN AMOUNT SUFFICIENT TO INCREASE THE CETANE NUMBER OF SAID FUEL. 